Systematic Study of Two-Pion Production in NN Collisions - from Single-Baryon to Di-Baryon Excitations

CELSIUS-WASA Collaboration, T. Skorodko*, M. Bashkanov, H. Clement, E. Doroshkevich, O. Khakimova, F. Kren, A. Pricking, G. J. Wagner

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The two-pion production in nucleon-nucleon collisions has been studied by exclusive and kinematically complete experiments from threshold up to T(p) = 1.36 GeV at CELSIUS-WASA. At near-threshold energies the total and differential distributions for the pi(+)pi(-) and pi(0)pi(0) channels are dominated by Roper excitation and its decay into N sigma and Delta pi channels. At beam energies T(p) > 1.1 GeV the Delta Delta excitation governs the two-pion production process. In the pi(+)pi(+) channel evidence is found for the excitation of a higher-lying I=3/2 resonance, favorably the Delta(1600). The isovector fusion processes leading to the deuteron and to quasi-stable (2)He, respectively, exhibit no or only a modest ABC-effect, i.e. low-mass enhancement in the pi pi-invariant mass spectrum, and can be described by conventional t-channel Delta Delta excitation. On the other hand, the isoscalar fusion process to the deuteron exhibits a dramatic ABC-effect correlated with a narrow resonance-like energy dependence in the total cross section with a width of only 50 MeV and situated at a mass 90 MeV below the Delta Delta mass.

Original languageEnglish
Title of host publicationHADRON 2009
Editors Crede, P Eugenio, A Ostrovidov
PublisherAMER INST PHYSICS
Pages520-524
Number of pages5
ISBN (Print)978-0-7354-0807-4
Publication statusPublished - 29 Aug 2010
Event13th International Conference on Hadron Spectroscopy - Tallahassee
Duration: 29 Nov 20094 Dec 2009

Publication series

NameAIP Conference Proceedings
PublisherAMER INST PHYSICS
Volume1257
ISSN (Print)0094-243X

Conference

Conference13th International Conference on Hadron Spectroscopy
CityTallahassee
Period29/11/094/12/09

Keywords

  • Roper excitation
  • Delta Delta excitation
  • Delta(1600)
  • ABC effect and resonance
  • PROTON-PROTON COLLISIONS
  • DOUBLE-PION PRODUCTION
  • ROPER RESONANCE
  • CROSS-SECTIONS
  • GEV-C
  • NUCLEON COLLISIONS
  • MESON PRODUCTION
  • ABC ENHANCEMENT
  • NEAR-THRESHOLD
  • S-WAVE

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